I don't believe it. I need more power?

[Irvrobinson]

I wonder if blink or a flash with the read light is really a big deal. Its certainly a far cry from "illuminated continuously for more than ten seconds." I'd call ATI and ask them about what a blink or flash means and if you are really out of headroom at that point. I'd be curious what they say.

It means at least one of the amp channels is momentarily clipping. That's bad. ATI employs a soft-clipping circuit so it doesn't sound terrible, but it causes compression.

[GranteedEV]

Irv, I wouldn't discount the possibility of the preamp or even the recording clipping. The clipping indicator on your amp only indicates a clipped waveform somewhere in the signal chain. That said, for those particular speakers I would want an amp that can deliver 700+w @ 4 ohm.

[QUOTE=TLS Guy;872499]So your speakers will draw 2.16 watts at 90 Hz from the amp to produce 86.4 db at I meter, versus 1 watt if it were 8 ohms. So the low impedance in the range where the power is has doubled the power requirement for your speakers versus 8 ohm ones.

So, slightly over half your amp power is heating up the crossover.

Now lets take a look at an active situation. Lets take my speakers.

The bass units are each 8 ohm, since there are two drivers of 8 ohms, each directly coupled to an amp sensitivity is 93 db 2.83 volts 1 meter and that will take one watt of power. You will have to provide at least 8.4 watts of power to achieve the same spl, and more likely 10 watts.

But there's a major difference. You're using two 10" drivers designed to operate in large boxes. The Salon2s use three 8" drivers designed to operate in relatively tiny boxes. Even active, those particular drivers wouldn't have high total sensitivity.

The real issue isn't passive vs active, but the need for people to have full range speakers, instead of sacrificing 20hz extension for midrange efficiency.

Now even with that situation I still need to provide 750 watts per speaker, to keep things relaxed at concert levels.

You mention 750 watts but if they're not operating in the same frequency range I don't see how you can just "add them up".

That is why good monitor companies like ATC and PMC provide about 3 to 4 KW per speaker and that is with active crossovers.

Those are not 3 to 4 kW - how can you realistically just add watts for amps operating in different frequency bands? That's just silly because they will never contribute that amount of power at a given frequency. It's like having a 2kw amp from 20hz to 80hz and a 100w amp from 40hz to 300hz. You do not have 2.1 kW of power, nor does that really even mean much due to difference sensitivities.

You're right that active systems don't have insertion losses, which might mean less heat in the crossover, but that doesn't make them any more efficient a system either. More amps means more idling power losses too - you really expect me to believe five amps is inherently "more efficient" than one amp? Especially if one of those amps is wasted on a tweeter where you might only need 10 watts anyways to hit the tweeter's mechanical limits. And that also means you can't just assume insertion losses affect total system performance either. So power is lost to insertion - the question is whether that affects performance.

So if you quote sensitivity at 2.83 volts 1 meter, then a four ohm speaker draws twice as much power from the amp as the 8 ohm one.

Now if you quote sensitivity at 1 watt 1 meter, then the four ohm speaker will be 3 db less sensitive than the 8 ohm speaker.

So his speakers are 83.4 db 1 watt 1 meter is sensitivity.

Years ago all speakers were quoted at 1 watt, 1 meter, which is the honest watt to do it, The 2.83 volts 1 meter was introduced to pull the wool over the eyes of the consumer.

I don't see how having a measurement that remains reasonably constant is inferior to a measurement which is frequency dependant....

They are 13 ohms between 2khz and 4khz - so they're 89db/w/m in that band. They're 8 ohm @ 1khz - so they're 86db/w/m in that band.

w/m is the one that puts the wool over the eyes of the consumer because watts are not a constant. With the correct amp, v are a constant.

The other issue is that power lost in the passive crossover is power not available to the drivers, and I was using that to illustrate the waste of amp power and pointing out that if it were an active design, then the sensitivity and spl would go up five to six db.

But... that's assuming the drivers would even appreciably... benefit from it. And no, sensitivity would not go up. You'd still be limited by the three very low sensitivity 8" woofers in the bass, and the 4" mid. The Salon 2s COULD be more sensitive if

A) They weren't made to fit inside small boxes (larger drivers, more sensitive drivers)
B) They didn't have an F3 near 18hz

The above are the real issues at play, not the passive crossover. Yes an active crossover means you could probably replace each of the ~10 ohm drivers a 4 ohm driver, which would get you some sensitivity (voltage) but wouldn't help efficiency (total power draw)

The fact is, even if the insertion loss exists, it does would not change the sensitivity of the three parallel bass drivers, which we assume are the limiting factor. It would only change the sensitivity of in the frequency range carried by the other drivers, however that is assuming they're meaningfully more sensitive to begin with.

Revel won't say how much power those Salon 2 take, but probably not much more than the OP is driving them with. I would doubt he can give them enough power to solve his problem.

Revel rates them at 1000W power handling.

[TLS Guy]

Irvrobinson

Which models? I spent quite a bit of time listening to the ATC SM150SL, and it was nowhere near that powerful. The website says 350w divided between the drivers. The imaging of the SM150 wasn't very impressive, incidentally. The speakers never disappeared in a pretty good set-up.

You mean these.



200 watts on the 15" driver, 100 watts to the mid and 50 watts to the tweeter.

I have no heard those speakers, but I have not heard an ATC speaker that was not correctly tonally balanced.

The problem with that speaker is what you have when you put a 15" driver on a flat baffle with the other drivers, even if you off set them. You have a problem with imaging right away.

So expense goes up to avoid it, as you have really complex carpentry.



And of course this.



The ATC SCM 300 ASL gives you 850 watts per speaker. To go higher, you have to have a custom speaker from them

The PMC BB5 XBD-A gives you 1650 watts per speaker, so 3.3 kW for the pair.



The BB-5A 1170 watts per speaker.

So I'm in that league with 750 watts per speaker, just about anyway.

[AcuDefTechGuy]

Here is the measurements of the Earthquake Sound amp (OEM is ATI AT3005):

"...two channels driving 8-ohm loads, began clipping at...1% distortion at 328.9 watts...Into 4 ohms, the amp began clipping at...1% distortion at 661.1 watts."

Earthquake Sound Cinénova Grande Five-Channel Amplifier Page 2 | Home Theater

[Irvrobinson]

Irv, I wouldn't discount the possibility of the preamp or even the recording clipping. The clipping indicator on your amp only indicates a clipped waveform somewhere in the signal chain.

That's an interesting possibility, and it crossed my mind. I'm using 35 feet of balanced cable and a Y-connector for inputs on the ATI channels and the DD18+. Perhaps the resulting impedance or some other electrical factor was stressing the preamp.

The problem with this theory is that my preamp is a Benchmark Media DAC1 HDR, and I discussed my planned configuration with a Benchmark engineer before ordering the unit. He assured me in a phone conversation that this sort of load would not be a factor at all for the HDR, and that even a 600 ohm load with 100 feet of balanced cable wouldn't affect performance in the slightest way. Moreover, the volume control was at the one o'clock position, which is within Benchmark's recommended range before changing the output padding. The HDR is shipped with a -20db padding, I've got my unit set to -10db, and I could use the 0db (no padding) position if I felt like it.

I haven't ordered a 'scope yet, but it looks like the amp is really clipping.

[TLS Guy]

Here is the measurements of the Earthquake Sound amp (OEM is ATI AT3005):

"...two channels driving 8-ohm loads, began clipping at...1% distortion at 328.9 watts...Into 4 ohms, the amp began clipping at...1% distortion at 661.1 watts."

Earthquake Sound Cinénova Grande Five-Channel Amplifier Page 2 | Home Theater

I'm going to get into an area where I think there is a lot of misunderstanding in these forums. The issue is the relationship to impedance, sensitivity, power demands and efficiency. Lets take a close look.

Now lets take your amp above, and lets have an 8 ohm impedance with a sensitivity of 2.83 volts 1 watt one meter and a speaker of four ohms 2.83 volts 1 watt 1 meter. Now the four ohm speaker will draw twice as much power from the amp for the same spl. So in effect the 8 ohm speaker is twice as efficient as the four ohm one.

So the power advantage of the lower impedance is totally negated.

Now as you know, few speakers have constant impedance with frequency. However an impedance curve does not correlate with the frequency response. In other words if the impedance rises to 30 ohms at a given frequency, the spl should be the same as it is at a frequency of four ohm impedance. However the speaker will be drawing much less power at the frequencies where the impedance is higher for the same spl

So for our speakers above lets say that at 100 Hz the impedance of the four ohm speaker is 4 ohm. Let is say the impedance is 32 ohms at 2kHz

So the four ohm speaker draws 8 watts for a given spl at 100 Hz, then for the same spl. at 2 kHz it will draw only 1 watt. So the speaker is 8 times more efficient at 2 kHz than at 100 Hz.

Now lets say the 8 ohm speaker has an impedance of 8 ohms at 100 Hz and 32 Ohms at 2 kHz. At 100 Hz it will draw 4 watts from the amp rather than the 8 watts of the four ohm one.

At 2kHz it will draw 1.3 watts.

So now lets go to the real world.

This is the impedance curve of the salon 2s.



From 20 to 600 Hz it is in the region of four ohms but at around 3 kHz it almost 14 ohms. So it will take four times 3.5 times the amp power for the same spl from 20 to 600 Hz as it does at 3 kHz.

Now lets take the impedance curve of the bass lines of my mains.

Now, there are two 10" driver driven from separate amps. The only way to measure the line was to parallel the drivers. So to get the impedance each amp sees you have to double the number.

So at 20 Hz each amp sees an impedance of 12 ohms at 30 Hz almost 24 ohms and at 100 Hz 8 ohms.

So at 100 Hz the amp has to deliver 3 times the power that it does at 30 Hz and and 1.5 times the power it does at 20 Hz.

With the two speakers side by side the sensitivity is 90 db 1 watt one meter, which is the same 90 db 1.83 volts 1 watt one meter since it is 8 ohm at that frequency. Now the OPs speakers are 83.4 db 1 watt one meter, or 86.4 db 1.83 volts 1 meter. So the Salons require four times the amp power at 100 Hz than mine do.

Now if you use the Salons full range then at 30 Hz the salons require a whopping 12 fold increase in power compared to mine.

Now lets get off track a little and look at the efficiency of superior loading in this case a well designed TL.

At 30 Hz these speakers only require one third of the power at 30 Hz versus 100 Hz.

The impedance curve correlates very well with the region of support of the drivers in a TL. So you can see support from 20 Hz to between 50 and 60 Hz. The impedance rises because of the high pressure behind the drivers is limiting and actively controlling cone excursion, significantly lowering distortion. It explains why the bass amps barely break a sweat even when the grandchildren are peeling with delight having their internal organs rearranged watching Real Steel.

Now the mid lines are tuned a half octave above the long bass lines.

If you look at the impedance curve you will see an impedance of 12 ohms at 46 Hz with the curve indicating broad support and driver control from 30 to 70 Hz. So if you work it out the efficiency in the difficult range of 20 to 80 Hz is very high.

The mids are also off loaded by sending the BSC to the upper 10" driver.

I think you can see that on a watt for watt basis it leaves all but horn loaded subs well behind in the dust.

So looking at the combination of impedance power and sensitivity, and looking at the relative efficiency changes in frequency gives you a much better guide to what is really going on.

Bottom line: - you focus on one number and you will surely come to an erroneous conclusion.

[Irvrobinson]

Irvrobinson

You mean these.



200 watts on the 15" driver, 100 watts to the mid and 50 watts to the tweeter.

I have no heard those speakers, but I have not heard an ATC speaker that was not correctly tonally balanced.

The problem with that speaker is what you have when you put a 15" driver on a flat baffle with the other drivers, even if you off set them. You have a problem with imaging right away.

Yup. Those are the ones I heard. A friend found a lightly used pair at a remarkable price, and I helped him set them up. That is one heck of a midrange driver, but I'm an imaging fanatic. IMHO, they're not much of a challenger to the Revel, and don't support the case at all that an active crossover design has a great advantage over a passive one.

Actually, the most compelling case I've heard for active crossovers is the Legacy Helix:

Helix | Legacy Audio - Building the World's Finest Audio Systems

Waaay too much speaker for me, but if you've got a huge room and massive funding it can produce live music sound levels.

[TLS Guy]

Yup. Those are the ones I heard. A friend found a lightly used pair at a remarkable price, and I helped him set them up. That is one heck of a midrange driver, but I'm an imaging fanatic. IMHO, they're not much of a challenger to the Revel, and don't support the case at all that an active crossover design has a great advantage over a passive one.

Actually, the most compelling case I've heard for active crossovers is the Legacy Helix:

Helix | Legacy Audio - Building the World's Finest Audio Systems

Waaay too much speaker for me, but if you've got a huge room and massive funding it can produce live music sound levels.

I have not heard the Revel's, but a passive crossover at 150 Hz has to be considered a poor design concept. Also the rise of impedance is occurring below 20 Hz.

Now I have been doing this for a half century now, and from what I see I would be confident of predicting a very poor sloppy ill defined bass.

This is given credence by you having to crossover at 80 Hz and that is what I would expect looking at the data. So a well designed smaller speaker with your sub would have got you to the same place and may be a better place.

[Irvrobinson]

I have not heard the Revel's, but a passive crossover at 150 Hz has to be considered a poor design concept. Also the rise of impedance is occurring below 20 Hz.

Now I have been doing this for a half century now, and from what I see I would be confident of predicting a very poor sloppy ill defined bass.

This is given credence by you having to crossover at 80 Hz and that is what I would expect looking at the data. So a well designed smaller speaker with your sub would have got you to the same place and may be a better place.

My need for a sub is a idiosyncratic room and placement phenomenon, not from "very poor sloppy ill-defined bass". On the contrary, there are placements for the Revels where the bass was very good, outstanding actually, but those placements were either inconvenient or compromised imaging. My choice for the 80Hz high-pass filter is due to the sub *and* the Revels sounding muddy together, when the Revels were running full-range.

The Revels are certainly not perfect speakers, and I'd swap them out if I found a better product that would fit in my room at a price I can afford, but your theory that they demonstrate some sort of sloppiness in the bass is not the case in my experience. It is also interesting to note that Legacy uses a 120Hz crossover in the Focus SE, and the KEF 207/2 (another speaker I admire) also uses a 120Hz crossover point, lower even than the Revel. None of these have sloppy, ill-defined bass. Speaker design is not one of my skills, but it seems mighty easy for a layman to find exceptions to your assertions.

[TLS Guy]

My need for a sub is a idiosyncratic room and placement phenomenon, not from "very poor sloppy ill-defined bass". On the contrary, there are placements for the Revels where the bass was very good, outstanding actually, but those placements were either inconvenient or compromised imaging. My choice for the 80Hz high-pass filter is due to the sub *and* the Revels sounding muddy together, when the Revels were running full-range.

The Revels are certainly not perfect speakers, and I'd swap them out if I found a better product that would fit in my room at a price I can afford, but your theory that they demonstrate some sort of sloppiness in the bass is not the case in my experience. It is also interesting to note that Legacy uses a 120Hz crossover in the Focus SE, and the KEF 207/2 (another speaker I admire) also uses a 120Hz crossover point, lower even than the Revel. None of these have sloppy, ill-defined bass. Speaker design is not one of my skills, but it seems mighty easy for a layman to find exceptions to your assertions.

I'm not familiar with the legacy or Focus, but the 120 Hz crossover is just a shelving BSC affair which you can get away with. A passive fourth order crossover at 150 Hz is another matter entirely. I don't care who does it, it is a bad idea. It is in this range were going to active crossover raise performance to a much higher level entirely. Yes, and I mean a much higher level.